| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage controlled oscillator in which the linearity of the change ratio of the oscillation frequency with respect to the control voltage is increased over a wide range of control voltage, without using a plurality of variable capacitance circuits. SOLUTION: A voltage controlled oscillator 100 comprises: an inductor circuit including inductors 101, 102; a variable capacitance circuit 110 which includes variable capacitance elements 111, 112 for changing a capacitance value in accordance with a voltage difference between both of two terminals thereof and capacitive elements 113, 114 for cutting a DC component, and which is connected in parallel to the inductor circuit; a negative resistance circuit including cross-coupled oscillating transistors 103, 104; and a time-switched level shift circuit 108 for shifting a reference voltage to be outputted to two or more levels in accordance with time. A connection point A is supplied with a control voltage Vt for controlling an oscillation frequency, and connection points B, C are supplied with a reference voltage Vref outputted from the time-switched level shift circuit 108 via resistors 115, 116. COPYRIGHT: (C)2008,JPO&INPIT
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